lithographischer projektionsapparat, method for the production of an article, the article and cannot be generated

摘要

PURPOSE: A lithographic projector is provided to accurately obtain a position of a movable table in the projector, by using two or more color interferometer devices by an arbitrary selection. CONSTITUTION: The apparatus comprises flushing gas means for supplying purge gas to a space accommodating at least a part of the movable table, the purge gas being selected such that leakage of the purge gas into the area of operation of the interferometric devices does not cause significant error in the interferometric measurements.